1. Field of the Invention
The present invention relates to a toner, a developer, a toner container and a latent electrostatic image carrier used for laser beam printer, facsimile, digital copier and the like. The present invention also relates to a process cartridge, an image forming method and an image forming apparatus using the above.
2. Description of the Related Art
Generally, an image forming method of an electrophotography imparts electric charge to a surface of an electrophotographic photoconductor by discharge, to thereby form a latent electrostatic image thereon by an exposure. Then, the latent electrostatic image on the photoconductor is to be developed with a toner, to thereby form a toner image. Thereafter, the toner image is to be transferred to a conveyed recording member such as paper and the like. The thus transferred toner image is to be fixed on the recording member, thus bringing about a final image.
A photoconductor used for the above image forming method, conventionally, was mainly an inorganic photoconductor such as selenium, zinc oxide, cadmium sulfide and the like. Presently, however, an organic photoconductor (OPC) is widely used in place of the inorganic photoconductor, due to its advantages such as selectivity of materials causing small pollution to the global environment, low manufacturing cost, high selectivity of exposing light source.
Due to its low mechanical strength, however, the organic photoconductor may cause wear to a photoconductive layer after repeated operations, failing to obtain sufficient chargeability, sensitivity and the like which are required properties.
Moreover, the organic photoconductor may cause image blur when ozone, NOx and the like adhere to a top surface, where the ozone, NOx and the like are caused by corona discharge in repeated copying processes, mainly in a charging operation. Moreover, the organic photoconductor may cause low resistance of the photoconductor's surface due to a filming phenomenon, thus lowering an image density. Herein, in the filming phenomenon, paper powder and the like caused when paper is used for a recording medium of fine-powder toner adhere to the photoconductor's surface. The above-described are problematical.
In sum, such a technology is desired as can continuously keep an initial photoconductor property by efficiently removing deposit even when a top surface of the organic photoconductor is polished gradually by some units after long-term repeated operations.
To meet the above requirement, for example, the following method is proposed: for an organic photoconductor having a surface protective layer made from a fluorine-contained amorphous silicon carbide or an amorphous carbon, using a toner which contains polishing fine particles meets both wear resistance and deposit removal (refer to Japanese Patent Application Laid-Open (JP-A) No. 2001-42551). The above proposed method is, however, high in manufacturing cost for film forming of the protective layer, thus lacking practicality.
Moreover, for example, the following method is proposed: for an organic photoconductor having a surface protective layer in which high-hardness fine particles are dispersed, a developer added by fine particles capable of functioning as polishing material is used (refer to JP-A No. 2001-228645). In this proposed method, however, dispersing the fine particles in the surface protective layer may decrease contact efficiency between a cleaning member and a photoconductor's surface, decreasing cleanability of toner remaining after transfer.
Moreover, for example, the following method is proposed: for an organic photoconductor having specified mass ratio of an electric charge mobile material and a polycarbonate, a toner having specified addition amount of additive is used, for meeting both wear resistance and filming resistance (refer to JP-A No. 2002-244314). This proposed method, however, does not satisfy rapid desire for higher durability, which is a problem in view of wear resistance of the photoconductor.
Objects and Advantages
It is an object of the present invention to provide a toner, a developer, a toner container and a latent electrostatic image carrier which are capable of obtaining a good image free from abnormal images such as those having image density decrease, image blur and the like, even after a long-term repeated operations. It is another object of the present invention to provide a process cartridge, an image forming method and an image forming apparatus which use the above.